THEATER REVIEW

Regular Singing

When a family gathering gets boring, you can either turn on the TV or split.

Not so at the intermissionless “Regular Singing,” which unfolds as members of the Apple clan share a dinner of leftovers.

They are smart, sensitive, thoughtful, polite — which is good in real life but not at the theater. So the show just hovers around with well-mannered dullness. Compared to it, “Waiting for Godot” seems like a Tom Clancy thriller.

“Regular Singing” is the fourth and last entry in Richard Nelson’s Apple family cycle, which started three years ago. The whole shebang can be seen in repertory at the Public, with the same exquisitely tuned ensemble cast — the main reason to catch this show.

All the plays take place around a living-room table in the home of Barbara Apple (Maryann Plunkett) in Rhinebeck, NY. All involve a meal, which is eaten by the actors in real time. And all are set on a highly symbolic date, on which each show also opened.

“That Hopey Changey Thing” was set on the midterm election of 2010. “Sweet and Sad” was on Sept. 11, 2011 and “Sorry” on Election Day 2012.

Now comes “Regular Singing,” in which the Apples gather on the 50th anniversary of the JFK assassination.

It’s not an official commemoration or anything like that, but what happened in Dallas back then is on their minds — even if what mostly concerns the Apples is the Apples.

And while each installment of the saga stands on its own, those who have seen them all will get more through aggregation, especially since the cast, for the most part, has remained the same.

It’s interesting to see what’s happened to Barbara’s brother, Richard (Jay O. Sanders), a lawyer. He used to work for the state attorney general, then for a lucrative firm, and now he’s with the Cuomo administration in Albany.

But the biggest change is Richard himself, who’s gone from being the liveliest, most cantankerous of the bunch to a mopey sad sack. Ever since splitting with his (unseen) wife, he’s become a shadow of his former self.

This is a problem because Richard could always be counted on to stir things up and provoke his sisters, who also include daffy writer Jane (Sally Murphy, stepping in for J. Smith-Cameron) and Marian (Laila Robins), an NPR-loving elementary-school teacher.

The last can always be counted on to toe the line. Problems signing up for health care? “They’re fixing that,” she says.

Homeless kids in the city? “De Blasio’s going to try and fix that.”

But without Richard’s provocations, all the Apples do is sit around, sing hymns and talk in aggrieved tones — they especially love factoids and anecdotes.

They also apply subdued, dignified forebearance to separations, illnesses and deaths — Marian’s (unseen) ex-husband is dying of cancer upstairs, and she uses a baby monitor to check on him.

This is heavy-duty enough, yet Nelson links his family drama to a national milestone, as if angling for extra gravitas points. He doesn’t earn them: What the Apples go through is far from inconsequential, but the show fails to transcend its intimate scope.